Fresh fruit and fresh vegetables deteriorate in most conditions encountered between harvest and ultimate consumption. This is more so where the fruit or vegetable has been subjected to a mechanical treatment that wounds such as peeling, coring, slicing, dicing and/or the like (hereafter “slicing”) and even more so when thereafter the produce is not refrigerated constantly.
By way of example mechanically treated fruits (e.g. apple slices) deteriorate rapidly in respect of a number of criteria following mechanical treatment (e.g. slicing) [e.g. taste, texture, browning, other visible spoilage and safety] and more so in “abusive” temperature conditions, i.e. above refrigeration temperatures such as 4° C. or above.
The apple hereafter will be used as an example of a fruit is subject to challenges which will adversely affect taste, texture, visible spoilage and food safety.
Many prior art procedures have been proposed for improving the performance of fresh fruit in refrigerated and/or unrefrigerated conditions but none adequately deals with fresh fruit or fresh vegetables where there is a mechanical disruption of the fruit or vegetable and where there is a prospect that downstream of such treatment there is a prospect of subjection at some stage to at least an abusive temperature range that may allow the growth of spoilage or pathogenic organisms and/or promote the deterioration of the product quality so it is unacceptable for eating. For example, where a fruit such as an apple is treated, there is the prospect downstream of its abuse by a manufacturer of abuse between the manufacturer and a distributor, at the distributor's premises, between the distributor and the retail outlet, in the store of the retail outlet, between the store and the display cabinets of the retail outlet, during display at the retail outlet, and between such display and the ultimate consumption away from the retail outlet by the customer.
Inherent also in at least most fresh fruit and at least most fresh vegetables is enzymatic browning which customarily has been addressed by treatments such as immersion and/or spraying with anti-browning agents such as calcium ascorbate or equivalent compositions which have the effect of inhibiting the polyphenol oxidase reaction to provide a protective effect.
An example of such a “calcium ascorbate” treatment is that of Mantrose Haeuser Co., Inc., disclosed in their U.S. Pat. No. 5,925,395 (in respect of vegetables) and U.S. Pat. No. 5,939,117 (in respect of fruit such as apples). These U.S. patents are hereby included by way of reference.
Other anti-browning treatments involving ascorbic acid and calcium ions include Ponting, J. D; Jackson, R; Watters, G. “Refrigerated Apple Slices: Preservative Effects of Ascorbic Acid, Calcium and Sulphites” Journal of Food Science, 1972, Vol. 37, 3, 434-436, Toivonen, P. M. A. “The Reduction of Browning in Parsnips” Journal of Horticultural Science, 1992, Vol. 67, 4, 547-551 and Mastrocola, D; Pittia, P, Lerici, C. R. “Quality of Apple Slices Processed by Combined Techniques” Journal Food Quality. Trumbull, Conn.: Food & Nutrition Press. April” 1996, 133-146.
In the last mentioned journal article (Mastrocola et al.) the effectiveness of single pre-treatments and combinations of pre-treatments on the prevention of enzymatic browning during freezing and thawing of apple slices was investigated. It discloses a combination of blanching and dipping, either of which alone could not control enzyme activity. They found the blanching of apple slices caused a significant decrease of firmness even before any freeze-thawing phase.
There has been disclosure of heat treatment regimes for fresh fruit and vegetables. In this respect I refer to Kim, D. M.; Smith, N. L.; Lee, C. Y. “Apple Cultivar Variations in Response to Heat Treatment and Minimal Processing” Journal of Food Science 1993, Vol 58, 5, 1111-1114, Kim, D. M.; Smith, N. L.; Lee, C. Y.; “Effective Heat Treatment on Firmness of Apples and Apple Slices” Journal of Food Processing and Preservation 1994 Vol 18, 1, 1-8 and C. O. Perera, C.Rollin, E. A. Baldwin, R. A. Stanley, M. S. Tian (2001) “Minimally processed Apple: Inhibitory effects of heat treatment on respiration and ethylene production”, Abstract 6 Session 96 IFT Annual Meeting New Orleans, Jun. 22-27 2001.
There has also previously been disclosure of the use of high energy electro magnetic radiation such as UV light or ionising radiation (e.g. gamma rays) for the preservation of fruit and/or vegetables. In this respect I refer to Chong Chon, Kim; “The Influence of Heat, Ultraviolet and Ethylene Absorber Treatments on Storage Life in Fuji Apples” Journal of the Korean Society for Horticultural Sciences, 1997, Vol. 38, 2, 153-156.
None of the prior art procedures however hitherto has satisfied a desire for a treatment procedure for fruit and/or vegetables that preferably is devoid of sulfites or other preservatives, and which satisfies food safety requirements as well as maintaining flavour, crispness and appearance where the fruit and/or vegetable has been subject to a mechanical treatment such as slicing and subsequently subjected to temperatures greater than 4° C. during storage and consumption.
The present invention in one of its aspects is directed to a method of treatment which will lead to improved shelf life over a procedure as disclosed in the aforementioned U.S. patents and provide over such an extended period a retention of flavour and texture whilst satisfying requirements for little or no browning nor other visible spoilage (such as that which is microbial—whether fungal and/or bacterial) and whilst satisfying food safety requirements insofar as, for example, micro organisms (such as Listeria) is concerned.
It is still another aspect of the present invention to provide an anti browning treatment which, if desired, can be integrated into an extended shelf life procedure or the extended shelf life procedures of the present invention.
We have determined a procedure that is applicable for fruits such as apples but is equally applicable to other fruits (such as pears and persimmons), and which is applicable to vegetables (such as, for example, squash, pumpkin, carrot and radish) which has an ability to improve shelf life of “sliced” (meaning any mechanically reduced pieces of some integrity) material for a period of say 21 days at low temperature but without a requirement for constant refrigeration below 4° C.
It is to this and any aspects of this that the present invention is directed.